April 2007 / April 2007 - Server Virtualization

One of the hottest topics in business technology today is Server Virtualization. But for all the talk, a lot of people still seem to be in the dark as to what exactly Virtualization is, and how it could affect their business. In this month’s Tech Brief we’ll take a look at what virtualization is, why it’s become so popular, and what you need to know about evaluating it for your business.

What is Server Virtualization?

In its simplest sense, server virtualization is the process of partitioning one physical server into multiple virtual servers that all have the appearance of being dedicated machines. Just as you can have multiple programs open at once in Windows, server virtualization allows you to have multiple servers operating at once on one physical system. Virtualization technology has actually been around since the 1960’s; but until recently it hadn’t been refined to the point where it was commercially viable.

How Does it Work?

There are actually many different virtualization methods, but for the most part the majority of virtualization solutions are based on one of three technologies.

Full Virtualization – Full Virtualization utilizes a software application (called a hypervisor) . The hypervisor acts as the physical server’s operating system (OS) and allows you to create new virtual servers and dedicate physical CPU and RAM to them. It also creates a separation between each virtual server and the physical server hardware. The hypervisor acts as go-between, relaying data from the virtual server to the physical server hardware. This separation allows you to install almost any Operating System (OS) to run on a virtual server without it being aware that it’s running virtually.

Full Virtualization offers the most comprehensive type of virtualization, but also requires powerful physical servers that must contain multi-core processors and a large amount of memory. VMware and Microsoft Virtual PC are two commercial examples of Full Virtualization solutions.

Para-Virtualization – Since the hypervisor in a Full Virtualization machine must manage multiple virtual servers at once and keep them independent of one another, it demands a great deal of processing power. Para-Virtualization reduces that demand by modifying each virtual server OS to recognize that it’s running in a virtual environment and can cooperate with the hypervisor. This allows for an increase in performance and responsiveness that is extremely close to that of physical, non-virtualized servers. Since the OS must be modified in Para-Virtualization, this method works best for open source operating systems such as Linux. Proprietary operating systems such as Windows, which can’t be modified, aren’t suitable. Examples of Para-Virtualization software include Xen, Win4Lin, and IBM’s Z/VM.

OS-Level Virtualization – The third method of server virtualization, OS-Level Virtualization, eliminates the hypervisor and gives its responsibilities to the server’s OS (Linux, Windows, Unix, etc.). So with OS-Level Virtualization, the operating system creates new virtual servers, allocates resources, and keeps the servers independent of each other. Since you’re running everything off one OS, all the virtual servers must all run the same operating system. Linux VServer, Virtuozzo, and OpenVZ are examples of OS-Level Virtualization.

What are its Benefits?

There are a wide-variety of uses for virtual servers. Some of the most applicable for businesses include:

Server consolidation – virtual servers can consolidate multiple physical servers onto one machine, which in turn saves space and power consumption. Server consolidation is also great for servers which may be infrequently used. For example, you may have an old application server which is used every few months. Instead of leaving the server on and wasting power when its not in use, or having the server turned off and taking the time to physically boot it up and connect to the network every time someone needs to access it – you can just create a virtual server that can be turned on with a few mouse clicks or left on constantly with very low power consumption.

Disaster recovery or high availability – if you have multiple physical servers dedicated to running virtual servers, transferring servers in the case of hardware failure or a disaster is easier than it would be to fail over to a redundant physical backup server. Virtual servers can be transferred from one machine to another almost instantaneously without the end-user even noticing. For example: if you have a power failure at your office and you have a second virtual machine in an offsite location, your virtual servers can be immediately transferred to the second machine.

Application testing – virtual servers are a great way to test or develop new applications without running the risk of them affecting your network. Also, depending on the virtualization program you use, you may be able to copy running virtual servers – in effect creating backup copies just in case you run into a problem during your testing session that would require a system reload / re-install. Recovery to the backup image can be accomplished much more quickly in a virtual test environment.

Is Virtualization Right for Your Business?

Whether to implement a virtual server infrastructure depends upon your organization’s needs and technology budget. At this time the additional hardware needed for virtualization can be cost prohibitive for many companies with standard network needs. But for organizations with a high dependence upon uptime, or for companies who do a great deal of hardware and software testing, server virtualization can be an incredibly worthwhile technology investment.

As with any new technology, you should consult with a trusted technology advisor prior to making a final decision on implementation. Staples Network Services by Thrive has professional experience with virtual servers and can answer any question you may have as well as help you to gauge whether implementing virtual servers makes sense for your business. Please contact SNS by Thrive if you would like to learn more.